Macdonald analyzes the results and interpretations of an earlier experimental work by Mitoff and Charles, in which it was concluded that observed capacitances were too large to be explained by space‐charge polarization due to blocking of a single mobile ion. These comments indicate the difficulties and uncertainties that arise in attempts to apply to this case two mobile ion models, in which the possibility of allowing the mobility of one of the ions to become zero is not explicitly accounted for.